hkcee - biology - 2000 - paper i - a.pdf

8/19/2019 HKCEE - biology - 2000 - paper I - A.pdf

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2000 CE Biology Paper I Marking Scheme

FOR TEACHERS' USE ONLY

Marks

rz.",l-t'O

(i)

The cells of A and the cells of the foetus are fonned by mitosis

of the zygote "".""'"

(ii) (1)

(2)

female I

A spenn ca"ying an X chromosome I

fused with an egg, which always contains an X chromosome ".'.'" I

to fonn a zygote I offspring with two X chromosomes. '... I

thus resulting in a female foetus

(iii)

There are 3 chromosomes 1 / an extra chromosome s present

(iv)

The foetus may be expelled out of the uterus I miscarriage '

I

(v)

)

)

) any

)

Blood from A to the foetus has

higher oxygen content

higher nutrient content

lower carbon dioxide content

lower urea content

(accept other correct answers)

Total: 10 marks

,(

.(b)

(i)

Tissue A is .palisade mesophyllissue B is .spongy mesophyll

I

1

(ii)

(iii)

Number of chloroplasts n region 1 s 20; while that n region 2 is 12 I

Ratio of chloroplast density n region 1 to that in region 2 is 5:3 I

,: " 0 o.

'_0.his allows."thc eaf to carry out pho~synthcsis ata higher rate 1

because issue A hasa higher ~ensityofchloroplasts 1

and it is located in the upper ayer of the leaf :. 1

so its cells are under direct illumination I can receivemore sunlight than

the cells oftissueB 1

Effective communication (C)

11

(iv)

Put the stem ofa leafy shoot in a dye solution for some time ~..~ut cross sections of the stem and the leaf """' ".""""'"

Examine the sections under the microscopeell type C would be stained by the dye '

Total: 12 + 1 marks

-.(

I. (c)

(i)

Oxygen in the tidal air diffuses through'the residualair '..." ""'... 1

and dissolves in the water film lining the air sac 1

It then diffuses across he walls of the air sac and he capilla[): nto the blood... 1

I Effective communication (C) i I

(I) The volume of tidal air will increase .' '..' ".'...""."...'.'.'." 1

(2) The oxygen uptake in the blood becomes aster I

(ii)

(iii)

because he distance of diffusion of oxygen rom the tidal air)

to the water film is reduced )

or because he surfaceareaof the air sac for diffusion of ) anyone 1

oxygen s increased )

Particles Tar depositon tii~ ~all of the air ~c 1

thus reduce he rate ofdiffiisionofoxygen ..., 1

(accept other correct anSWers) ..".

.,: .,1,:... '~ '. .:'

Total: 8 + 1 marks

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-H'B...g FOR EACHERS'SEONLY

2000 CE Biology Paper 1 Marking Scheme .Marks

2. (a) (i) The daily energy intake of Jane is 6620 kJ """ '" I

which is less than her daily energy requirement I

Thus she has to consume I mobilize the fall food reserve in her body : I

~t;o ~~:;;:=~~~~h t ,

L-~=::~:~=~ .-- -l

ij) Amino acids are broken down in the liver I

to form carboh~drafC a part without nitrogen (and urea) ".'" '.'.' I

which will be oxidized/used in respiration to release energy I

(iii) anaemia '."" """'" "." ". I

(iv) Rub a piece of ham on a filter paper m translucent spot will remain after drying I

Immerse the paper in an organic solvent and the spot will disappear 1 any

OR one

Add alcohol to a piece ofham and obtain a clear solution m set

Add water to the clear solution I

The solution will turn milky 1

" .A + I marks

.(b> I

(i)

-

(ii)

.u..I: au

F ro m I t o S u ni s o f l g ht i nt en s y , t he s z e o f t he p up i d ec re as es

w h increasing lght intensiyowever, when the lght intensy is above S unis

t he s iz e o f t he p up i w r em ai n u nc ha ng ed w h i nc re as ng l gh t i nt en si yh is re sp on s e h elp s to p rev en t ex ce s s ve lg h t e nte rin g th e e y e. . . ' "o th at th e lg h t-s en s iv e c els o f th e re tin a ma y n o t b e d amag edg ht-se n si iv e c els / p h oto rc ce p to rs -+ s en s ory n e u ro ne / o pt ic n e rv e

-+ associatinn neurnn.c in .-+ motor neurone / nerve -+ iis muscle

( I f : ma rk fo r e a ch te nn ) Ded u c I f : mark i th ere is n o a r ro w s ign .ecause al the lght entering the eye is absorbed by the retina and the choroids a resul no lght is refleced out of the eye through the pupi

(iii)

3

I

iv)

I

Total: 9 marks

Advantage:

The chanceof pollination fertilization is higher )

Lesswastage f pollen grains ) anyone I

Desirable characters of the parent are more likely to be transmitted)

to the offspring )

Disadvantage:

Lessgenetic variation (accept ther con-ect nswers) I

Remove he anthers rom the flower before heyare mature I

Use a brush o dust pollengrains of another ea flower onto the stigma of this flower I

Cover he flower with a plastic bag o prevent urther pollination ". ...' I

Effective communication (C) 1

(I) Greenpod colour s dominant o yellow pod colour I

or The allele for greenpod colour s dominant o the all~le for yellow pod colour

(2) Let G represent the allele for green pods I

and g representhe allele for yellow pods

F, Gg X Gg I

It~ It~

Gamete C(;:~~a 1

Fz GG Gg Gg gg t

' Y. "'

gree~POd: yello7 pod } I

Deduct 1 mark for leaving out the abels ofF., gameteand Fz..

Total: 11 + I marks

(i)

(ii)

( -"

(iii)

2000-CE-BIO 1-9 .-

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.R Pi ~ ftiJi fJD

2000 CE Biology Paper 1 Marking Scheme


Marks

3. (a)

(I) Blood capillary2) Its wall is one-cell thick I the diameter of the lumen is

slightly greater than or similar to that of a red blood cellhe pressure of blood in A is higher than the pressure of

the fluid surrounding the muscle cellshis forces the plasma except the plasma protein out of Arawing (D): clear and accurate diagram. double line for capillary wall,

biconcave RBC "",."",.,.",.,.,."""",.,.."..,."",

Labels (L): any three of the following labels and title; '/z mark each

(i)

1+

(ii)

(iii)

lYJ.

lYJ.

nucleus

cell of capillary wall/capillary wall

red blood cell

lumen I blood plasma I blood

A section alon~ line BC

{

(iv)

(small intestine) -+ hepatic portal vein -+ liver -+ hepatic vein -+ vena cava-+

heart -+ pulmonary artery -+ (lung) (Yz mark for each term)Deduct Yz mark if there is no arrow sign. I

Total: 10 marks

3

(i)

(ii)

(iii)

(iv)

(

Diabetes s caused y the absence f certain substance(s) I

which canbe found in the pancreas I

To detennine whether he substance n the pancreasextracteffective in

treating diabetes s a protein I

ora fat , I

Symptoms of diabetes would remain I

This is because rotease n the alimentary canal I

will digest he active substancewhich is protein in nature I

In the diabetic person, he pancreas annotproduce enough nsulin... 1

Thus the liver cannotconvertexcessglucose n the blood into glycogen 1

His blood glucose concentration emains high 1

leading o a high level of glucose n the glomerular filtrate 1

The kidney ubules cannot eabsorball the glucose from the filtrate ,. I

thus glucose s excreted n the urine

I Effect~vecommunication (C) i I

Total: 12 + 1 marks

(i)

(ii)

(iii)

The water potentialof the cell sapof cell A is greater han that of

the sucrosesolution 1

Water moves out of the cell by osmosis 1

The vacuole shrinks n size 1

pulling the cytoplasm/cell membraneaway rom the cell wall 1

I ~jfec~ve o;;;:'unicatwnC) .-- J

The waterpotential of the cell sapof cell B may be the same lower than

that of the surrounding solution 1

(acceptother easonableanswers)

(I) Adjust the positinn nfthe slide until cell A is at he centre of

the field of vision 1

(2) Adju~ the diaphra~m condenser o increase he illwnination

of the slide 1

rum the ad_iustmentnob until the cell is in focus 1

Total: 8 + 1 marks



R ~.R ft~~ IJU

2000 CE Biology Paper 1 Marking Scheme


Marks

4. (a)

(i)

The amylase converts starch nto maltose.

(ii)

To ensure hat sufficient amountof maltose s produced

(jij)

When he temperature ncreases rom O.'70°C.he amylaseactivity increases..., 1

When he temperatures ncreases rom 70-90°C. he amylaseactivity decreases. 1

The optimum temperature or the activity of barley amylase s 70°C 1

(iv)

Keep the mixture at very low temperature (below IO.C)he amylase is inactive at this temperature "."""'.'.'.""".".".""

but it is not denatured destroyed ..".

(v)

After incubating the mixture at a given temperature for a fixed period of time,

perform the Benedict's testeasure the amount of red precipitate / reducing sugar formed ", "

Total: 10 marks

4. (b)

(i)

(1)

High concentrationof suspended olids reduces he light intensity

in water I

Thus the rate of photosynthesis f the producers ecreases... I

and his leads o a drop in the populationof the producers I

I Effective communication (C)- --11

SiteD I

:~~(~

(2)

(ii) (1)

The greater the amount of organic pollutants in water. the higher

the bacterial population 1

because the organic pollutants provide food 1

for the growth I multiplication of bacteria I

(2)

Site C ,

(3)

Slow water current n the harbour

There is sewageoutfall at this site

Large human population

)

) anyone .

(iii)

To protect endangered speciesaccept other correct answers)

Total: 10 + I marks

4. (c)

(i)

When perfonning heavy exercise, rate of sweat production was faster

This was because large amount of heat was generated by the body

during exercisehe body temperature started to increasend this stimulated the increase in sweat production

I

(~I

I

I

(ii)

(iii)

When he person s performing exercise,a large amountof water in the

body was lost in the form of sweat 1

The water potential of the blood / plasmawas owered 1

Thus a greaterproportion of water was reabsorbed rom the glomerular filtrate.. 1

hence essurine was produced

I Effective communicat;on (C) 11

(I) The lining of the air sacs or respiratory ract is moist / covered with

a water film 1

Water in the water film evaporates nto the air of the air sac

respiratory ract 1

and is lost during exhalation

because he rate and depthof breathingwas ncreased ., I

so greateramountof air was exhaled rom the lungs per unit time I

leading to an increased ate of water oss hrough exhalation

Total: 10 + I marks

(2)

hkcee - biology - 2000 - paper i - a.pdf

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